curvature versus slope
  n = 419908 
  X=0, Y = 11.48 +/- 8.92 
  Weighted least-squares fit:  Y = 19.2 + 4.142 X  + -0.04721 X**2 

slope versus dZ, curvature < 5
  n = 228554 
  X=0, Y = 10.73 +/- 5.02 
  Weighted least-squares fit:  Y = 8.7 + 0.137 X  + 0.00220 X**2 
     at X = 100, Y = 44.5 
     effective RMSE xy = 68.5 

slope versus dZ, curvature < 15
  n = 295024 
  X=0, Y = 11.06 +/- 5.39 
  Weighted least-squares fit:  Y = 8.4 + 0.222 X  + 0.00173 X**2 

curvature versus dZ, slope < 10
  n = 196073 
  X=0, Y = 9.69 +/- 4.65 
  Weighted least-squares fit:  Y = 9.3 + 0.741 X  + 0.08744 X**2 


Number of samples 425526
Max dz = 900
Mean dz = 20
RMS dz = 47.8225888049
100cm = 96.8027805586 percentile value of dz